PI3K/Akt信号通路在七氟醚后处理减轻大鼠局灶性脑缺血再灌注损伤中的作用

目的 评价磷脂酰肌醇3激酶/蛋白质丝氨酸苏氨酸激酶(PI3K/Akt)信号通路在七氟醚后处理减轻大鼠局灶性脑缺血再灌注损伤中的作用.方法 雄性SD大鼠64只,体重300～350 g,随机分为4组(n=16):局灶性脑缺血再灌注组(IR组)、七氟醚后处理组(SP组)、七氟醚后处理+Wortmannin组(SW组)和Wortmannin组(W组).采用电凝法阻断左侧大脑中动脉,夹闭双侧颈总动脉60 min恢复灌注的方法制备大鼠局灶性脑缺血再灌注模型.再灌注即刻SP组和SW组吸入2.5%七氟醚60 min,夹闭双侧颈总动脉30 min时SW组和W组股静脉输注Wortmannin 0.6 mg/kg.于再灌注24、48、72 h时行神经功能评分,最后1次评分后处死大鼠取脑,测定脑梗死体积,采用Western blot法检测左侧脑组织磷酸化Akt(p-Akt)和磷酸化Bad(p-Bad)的表达水平.结果 与IR组相比,SP组和SW组各时点神经功能评分升高,再灌注72 h时脑梗死体积比降低,脑组织p-Akt和p-Bad表达上调(P＜0.05),W组上述指标差异无统计学意义(P＞0.05);与SP组相比,SW组各时点神经功能评分降低,再灌注72 h时脑梗死体积比升高,脑组织p-Akt和p-Bad表达下调(P＜0.05).结论 PI3K/Akt信号通路激活后p-Bad表达上调可能参与了七氟醚后处理减轻大鼠局灶性脑缺血再灌注损伤的过程.     

N-myc下游调节基因2在七氟醚预处理减轻大鼠局灶性脑缺血再灌注损伤中的作用

目的 评价N-myc下游调节基因2(NDRG2)在七氟醚预处理减轻大鼠局灶性脑缺血再灌注损伤中的作用.方法 健康雄性成年SD大鼠48只,体重280～320 g,采用随机数字表,将大鼠随机分为3组(n=16):假手术组(S组)、脑缺血再灌注组(I/R组)和七氟醚预处理组(Sev组).采用大脑中动脉阻断法制备大鼠局灶性脑缺血再灌注模型.大鼠吸入2％七氟醚lh,每天1次,连续5d行七氟醚预处理.Sev组于七氟醚预处理结束后24h制备局灶性脑缺血再灌注模型.再灌注24h时行神经功能评分,随后处死大鼠,取脑组织,测定脑梗死体积百分比,采用Western Blot法测定缺血半暗带区NDRG2和活化的Caspase-3的表达,采用免疫组织荧光测定缺血半暗带区NDRG2的表达及定位.结果 与S组比较,I/R组和Sev组脑梗死体积百分比升高,神经功能评分降低,脑组织缺血区半暗带NDRG2和活化的Caspase-3表达上调(P＜0.05);与I/R组比较,Sev组脑梗死体积百分比降低,神经功能评分升高,脑组织缺血区半暗带NDRG2和活化的Caspase-3表达下调(P＜0.05).Sev组核内NDRG2阳性染色较I/R组减浅.结论 七氟醚预处理可能通过抑制脑组织NDRG2的表达、活性和细胞凋亡,从而减轻大鼠局灶性脑缺血再灌注损伤.     

线粒体ATP敏感性钾通道在七氟醚预处理减轻大鼠脑缺血再灌注损伤中的作用

目的 探讨线粒体ATP敏感性钾通道(mito-K_(ATP)通道)在七氟醚预处理减轻大鼠脑缺血再灌注损伤中的作用.方法 健康雄性SD大鼠100只,体重250～300 g,随机分为5组(n=20):假手术组(S组)、缺血再灌注组(I/R组)、七氟醚预处理组(Sevo组)、mito-K_(ATP)通道阻断剂5-羟基葵酸(5-HD)组及5-HD+七氟醚预处理组(5-HD+Sevo组).采用线栓法制备大鼠局灶性脑缺血再灌注模型,七氟醚预处理方法:吸入2.4%七氟醚60 min后吸入纯氧洗脱15 min,停止吸入七氟醚后24 h时制备脑缺血再灌注模型.分别于再灌注6、24 h时进行神经功能损伤评分,计算脑梗死体积百分比,采用Western blot法测定蛋白激酶Cε(PKCε)膜转位水平.结果 与S组比较,其余各组大鼠再灌注6、24 h时神经功能损伤评分升高,脑梗死体积百分比及脑组织PKCε膜转位水平升高(P<0.05);与I/R组、5-HD组及5-HD+Sevo组比较,Sevo组大鼠再灌注6、24 h时神经功能损伤评分降低,脑梗死体积百分比降低,再灌注6 h时脑组织PKCε膜转位水平升高(P<0.05).结论 mito-K_(ATP)通道介导了七氟醚预处理减轻大鼠局灶性脑缺血再灌注损伤的作用,其机制可能与调控PKCε膜转位有关.     

8%乳化异氟醚后处理对大鼠局灶性脑缺血再灌注损伤的影响

目的 探讨8%乳化异氟醚后处理对大鼠局灶性脑缺血再灌注损伤的影响.方法 健康成年雄性SD大鼠48只,体重260～300 g,随机分为6组(n=8):假手术组(S组)、缺血再灌注组(I/R组)、低、中、高剂量乳化异氟醚后处理组(L-EI组、M-EI组和H-EI组)和脂肪乳组(LE组).除S组外,均采用大脑中动脉阻闭2 h,再灌注24 h的方法建立局灶性脑缺血再灌注模型.L-EI组、M-EI组和H-EI组分别于再灌注即刻腹腔注射8%乳化异氟醚3.5、7.0、10.5 ml/kg,LE组给予30%脂肪乳10.5 ml/kg,S组与I/R组不给药.再灌注24 h时行神经功能缺陷评分(NDS),取脑组织测定脑梗死体积.结果 与S组比较,其余各组NDS评分升高,脑梗死体积增大(P＜0.01);与I/R组比较,M-EI组和H-EI组NDS评分降低,脑梗死体积减小(P＜0.01),L-EI组和LE组上述指标差异无统计学意义(P＞0.05);与M-EI组比较,H-EI组NDS评分降低,脑梗死体积减小(P＜0.05).结论 8%乳化异氟醚后处理可减轻大鼠局灶性脑缺血再灌注损伤,且与剂量有关.     

七氟醚后处理对脑缺血/再灌注损伤大鼠的脑保护作用及对ROS/TXNIP/NLRP3通路的影响

目的探究七氟醚后处理对脑缺血/再灌注(ischemia/reperfusion,I/R)损伤大鼠的脑保护作用及对活性氧(reactive oxygen species,ROS)/硫氧还蛋白结合蛋白(thioredoxin interacting protein,TXNIP)/NOD样受体相关蛋白3(NOD-like receptor associated protein 3,NLRP3)信号通路的影响。方法60只SD雄性大鼠按随机数字表法分为假手术组(sham组)、I/R组、七氟醚后处理组(SP组),每组20只。采用大脑中动脉线栓法制备脑I/R模型,SP组造模后即刻吸入2.4%七氟醚30 min。对各组大鼠进行神经功能缺损评分;获取大鼠脑组织,H-E染色和2,3,5-氯化三苯基四氮唑(2,3,5-triphenyltetrazolium chloride,TTC)染色观察组织病理学变化和脑梗死体积;分析大鼠脑水肿程度及血脑屏障通透性;TUNEL法检测脑组织细胞凋亡率;检测血清炎性因子(IL-1β和IL-18)及脑组织氧化应激指标[ROS、丙二醛(malondialdehyde,MDA)、超氧化物歧化酶(superoxide dismutase,SOD)和谷胱甘肽过氧化物酶(glutathione peroxidase,GPx)]的水平;Western blot法检测TXNIP/NLRP3通路相关蛋白[TXNIP、NLRP3、凋亡相关点样蛋白(apotosis-associated speck-like protein containing a CARD,ASC)、半胱氨酸天冬氨酸酶-1(cysteine aspartase,caspase-1)]的表达。结果与sham组比较,I/R组大鼠神经功能缺损评分、脑梗死体积明显升高(P<0.05),脑组织水肿程度及血脑屏障通透性也明显增加,脑细胞凋亡率升高(P<0.05),血清IL-1β和IL-18含量明显升高(P<0.05),脑组织中ROS和MDA含量及TXNIP、NLRP3、ASC和caspase-1蛋白表达水平均明显升高(P<0.05),而GPx和SOD活性降低(P<0.05);与I/R组比较,SP组神经功能缺损评分和脑梗死体积降低(P<0.05),脑水肿程度及血脑屏障通透性下降,脑细胞的凋亡率降低(P<0.05),血清IL-1β和IL-18含量明显降低(P<0.05),脑组织中ROS和MDA含量及TXNIP、NLRP3、ASC和caspase-1蛋白水平明显降低(P<0.05),而GPx和SOD活性升高(P<0.05)。结论七氟醚后处理能够有效减轻大鼠脑I/R损伤,可能与其对ROS/TXNIP/NLRP3信号通路的抑制有关。     

七氟醚后处理对局灶性脑缺血-再灌注损伤的保护作用

目的评价在缺血后期及再灌注早期吸入不同浓度的七氟醚行后处理对大鼠局灶性脑缺血-再灌注损伤的保护作用及其剂量依赖性。方法雄性SD大鼠50只,随机分为空白对照组、吸氧组和0.5、1.0、1.5MAC七氟醚后处理组,每组10只。采用大脑中动脉线栓法阻闭(middle cerebral artery occlusion,MCAO)120min后再灌注72h制备局灶性脑缺血模型。各七氟醚后处理组于再灌注即刻的前20min和后10min给予不同浓度七氟醚吸入。再灌注后的24、48和72h行神经功能评分(NDS),并于最后一次评分后测定脑梗死容积比。结果0.5、1.0和1.5MAC组的脑梗死容积比分别为0.39±0.03,0.31±0.03和0.24±0.03(P<0.05),明显小于对照组0.53±0.05(P<0.05)。吸氧组为0.51±0.05,与对照组比差异无统计学意义。各个时间点七氟醚后处理组NDS明显优于对照组和吸氧组。结论在局灶性脑缺血-再灌注的缺血后期和再灌注早期吸入0.5、1.0和1.5MAC七氟醚行后处理均具有脑保护作用,并呈现剂量依赖性。     

乳化异氟醚预处理对大鼠局灶性脑缺血再灌注时脑组织突触后致密物质95活化的影响

目的 探讨乳化异氟醚预处理对大鼠局灶性脑缺血再灌注时脑组织突触后致密物质95(PSD95)活化的影响.方法 雄性清洁级SD大鼠32只,体重280 ～ 300 g,采用随机数字表法,将大鼠随机分为4组(n=8):假手术组(S组)、缺血再灌注组(I/R组)、乳化异氟醚组(EI组)和脂肪乳剂组(LE组).采用大脑中动脉阻塞法制备局灶性脑缺血再灌注模型.EI组和LE组分别腹腔注射8％乳化异氟醚10.5 ml/mg或30％脂肪乳10.5 ml/mg,24h后制备模型.再灌注6h时行神经功能缺陷评分,随机取4只大鼠,处死后取缺血侧海马和皮层组织,采用Western blot法检测磷酸化的PSD95( pPSD95)的表达水平.再灌注24 h时,随机取4只大鼠,处死后取脑组织,计算脑梗死体积百分比.结果 S组未见神经功能缺陷和脑梗死发生.与S组比较,I/R组、EI组和LE组神经功能缺陷评分、脑梗死体积百分比、海马和皮质pPSD95表达水平升高(P＜0.01);与I/R组比较,EI组神经功能缺陷评分、脑梗死体积百分比、海马和皮质pPSD95表达水平降低(P＜0.05),LE组差异无统计学意义(P＞0.05).结论乳化异氟醚可通过抑制脑组织PSD95的活化,减轻大鼠局灶性脑缺血再灌注损伤.     

七氟醚预处理对局灶性脑缺血再灌注损伤大鼠海马TREK-1表达的影响

目的 探讨七氟醚预处理对局灶性脑缺血再灌注损伤大鼠海马机械敏感性钾通道TREK-1表达的影响.方法 健康雄性SD大鼠36只,体重240～280 g,随机分为3组(n=12):假手术组(S组)、局灶性脑缺血再灌注组(l/R组)和七氟醚预处理组(Sevo组).结扎右侧颈总动脉、颈外动脉,采用线栓法阻断颈内动脉2 h,再灌注24 h制备大鼠局灶性脑缺血再灌注损伤模型;Sevo组于缺血前1 h经半密闭的吸入箱持续吸入含2.5%七氟醚的02;S组仅分离并结扎右侧颈总动脉、颈外动脉,不置入线栓.各组于再灌注24 h时行神经功能缺陷评分后断头取脑,TIC染色后测定脑梗死体积,采用RT-PCR法测定海马TREK-1 mRNA的表达.结果 与S组相比,I/R组和Sevo组神经功能缺陷评分和脑梗死体积比升高(P<0.01);与I/R组相比,Sevo组神经功能缺陷评分和脑梗死体积比降低,海马TREK-1 mRNA表达上调(P<0.05).结论 七氟醚预处理可通过激活海马TREK-1减轻大鼠局灶性脑缺血再灌注损伤.     

七氟醚麻醉对局灶性脑缺血再灌注大鼠脑组织水通道蛋白9表达的影响

目的 评价七氟醚麻醉对局灶性脑缺血再灌注大鼠脑组织水通道蛋白9( AQP-9)表达的影响.方法 成年雄性SD大鼠75只,体重230～270 g,采用随机数字表法,将其随机分为3组(n=25):假手术组(S组)、缺血再灌注组(UR组)和七氟醚麻醉组(SE组).S组和I/R组静脉注射芬太尼10μg/kg后静脉输注芬太尼25μg·kg-1·h-1,吸入65％N2O和35％O2;SE组吸入2.0％七氟醚和35％ O2.I/R组和SE组采用线栓法制备大鼠局灶性脑缺血再灌注模型,缺血2h后恢复灌注.分别于再灌注6h、1、2、3和5d时测定神经功能缺陷评分和脑组织AQP-9表达,计算脑肿胀率.结果 与S组比较,I/R组和SE组再灌注6h、1、2、3和5d时神经功能缺陷评分升高,再灌注1、2、3d时脑肿胀率升高,再灌注1、2、3和5d时脑组织AQP-9表达上调(P＜0.05);与I/R组比较,SE组再灌注2和3d时神经功能缺陷评分下降,脑肿胀率降低,再灌注2、3和5d时脑组织AQP-9表达上调(P＜0.05).结论 七氟醚麻醉减轻大鼠局灶性脑缺血再灌注损伤的机制与上调脑组织AQP-9的表达有关.     

异氟醚预处理对兔局灶性脑缺血再灌注时降钙素基因相关肽和NF-κB的影响

目的 探讨异氟醚预处理对兔局灶性脑缺血再灌注时降钙素基因相关肽( CGPP)和NF-κB水平的影响.方法 新西兰纯系家兔54只,雌雄不拘,体重2.0～2.5 kg,采用随机数字表法,将其随机分为3组(n＝18):假手术组(S组)、脑缺血再灌注组(I/R组)和异氟醚预处理(I组).麻醉下气管内插管,机械通气,S组和I/R组静脉输注咪达唑仑维持麻醉;I组吸人1.4％异氟醚30 min后洗脱10 min进行异氟醚预处理,然后制备脑缺血再灌注损伤模型,在脑缺血再灌注损伤过程中静脉输注咪达唑仑,3组静脉输注芬太尼和维库溴铵.I/R组和I组采用线栓法制备局灶性脑缺血再灌注损伤模型,于缺血2h时进行再灌注.分别于麻醉前和再灌注即刻、1h、2h、3h、4h、5h时取耳中央动脉血样,测定血浆CGRP浓度,各时点取完血样后立即处死动物,测定脑组织神经元NF-κB活性及其表达.结果 与S组比较,I/R组血浆CGRP浓度、脑组织神经元NF-κB活性升高,脑组织NF-κB表达上调(P<0.05);与I/R组比较,I组血浆CGRP浓度升高,脑组织神经元NF-κB活性降低,脑组织NF-κB表达下调(P<0.05).结论 异氟醚预处理减轻兔脑缺血再灌注损伤的机制与促进CGRP释放及抑制神经元NF-κB功能有关.     

Vasopressor hormone response following mesenteric traction during major abdominal surgery

Background : We investigated the vasopressor hormone response following mesenteric traction (MT) with hypotension due to prostacyclin (PGI₂) release in patients undergoing abdominal surgery with a combined general and epidural anesthesia. Methods : In a prospective, randomized, placebo-controlled study we administered 400 mg ibuprofen (i.v.) in 42 patients scheduled for abdominal surgery. General anesthesia was combined with epidural anesthesia (T4-L1). Before as well as 5, 15, 30, 45, and 90 min after MT we recorded plasma osmolality, hemodynamics and measured 6-keto-PGFlα (stabile metabolite of PGI₂), TXB₂ (stabile metabolite of thromboxane A₂) active renin, and arginine vasopressin (AVP) plasma concentrations by radioimmunoassay. Catecholamine levels were assessed by high-pressure liquid chromatography (HPLC) with electrochemical detection. Results : Following MT, arterial hypotension occurred along with a substantial PGI₂ release. This was completely abolished by ibuprofen administration. Although plasma levels of 6-keto-PGF_1α (1133 (708) vs. 60 (3) ng/L, median (median absolute deviation), P=0.0001, placebo vs. ibuprofen) remained significantly elevated, blood pressure was restored within 30 min after MT in the placebo group. At the same point in time plasma concentrations of TXB² (164 (87) vs. 58 (1) ng/L, P=0.0001), epinephrine (46 (33) vs. 14 (6) ng/L, P=0.001), AVP (41 ± (18) vs. 12 (7) ng/L, P=0.0004), and active renin (27 (12) vs. 12 (4) ng/L, P = 0.001) were significantly higher in placebo-treated patients. Conclusion : Under combined general and epidural anesthesia arterial hypotension following MT due to endogenous PGI₂ release is associated with enhanced release of AVP, active renin, epinephrine and thromboxane A₂, presumably contributing to hemodynamic stability within 30 min after MT.     

A Teaspoon Pump for Pumping Blood with High Hydraulic Efficiency and Low Hemolysis Potential

Abstract: Virtually all blood pumps contain some kind of rubbing, sliding, closely moving machinery surfaces that are exposed to the blood being pumped. These valves, internal bearings, magnetic bearing position sensors, and shaft seals cause most of the problems with blood pumps. The original teaspoon pump design prevented the rubbing, sliding machinery surfaces from contacting the blood. However, the hydraulic efficiency was low because the blood was able to "slip around" the rotating impeller so that the blood itself never rotated fast enough to develop adequate pressure. An improved teaspoon blood pump has been designed and tested and has shown acceptable hydraulic performance and low hemolysis potential. The new pump uses a nonrotating "swinging" hose as the pump impeller. The fluid enters the pump through the center of the swinging hose; therefore, there can be no fluid slip between the revolving blood and the revolving impeller. The new pump uses an impeller that is comparable to a flexible garden hose. If the free end of the hose were swung around in a circle like half of a jump rope, the fluid inside the hose would rotate and develop pressure even though the hose impeller itself did not "rotate"; therefore, no rotating shaft seal or internal bearings are required.     

Microspheres Based Detoxification System: A New Method in Convective Blood Purification

Abstract: A variety of protein-bound or hydrophobic substances, accumulating as a result of pathologic conditions such as exogenous or endogenous intoxications, are removed poorly by conventional detoxification methods because of low accessibility (hemodialysis), insufficient adsorption capabilities (hemosorption), low efficiency (peritoneal dialysis), or economic limitations (high-volume plasmapheresis). Combining advantages of existing methods with microspheric technology, a module-based system was designed. Major operating parameters of the latter can be modified to allow for adjustment to individual clinical situations. An extracorporeal blood circuit including a plasmafilter is combined with a secondary high-velocity plasma circuit driven by a centrifugal pump. Different microspheric adsorbers can be combined in one circuit or applied in sequence. Thus, a prolonged treatment can be tailored using specially designed selective adsorber materials. Comparing this system with existing methods (high-flux hemodialysis, molecular adsorbent recycling system), results from our in vitro studies and animal experiments demonstrate the superior efficiency of substance removal.     

Tissue perfusion in relation to cardiac output during continuous positive-pressure ventilation and administration of propranolol or verapamil

Background : Our objective was to determine whether administration of propranolol or verapamil modifies the hemodynamic adaptation to continuous positive-pressure ventilation (CPPV), in particular the regional distribution of cardiac output (CO).
Methods : General hemodynamics and regional blood flows assessed by microsphere technique (15 (μm) were recorded in 16 anesthetized pigs during spontaneous breathing (SB) and CPPV with 8 cm H₂O end-expiratory pressure (CPPV8) before and after intravenous administration of propranolol (0.3 mg · kg⁻¹ followed by 0.15 mg · kg⁻¹ · h⁻¹, n=8) or verapamil (0.1 mg · kg⁻¹ followed by 0.3 mg · kg⁻¹ · h⁻¹, n=8).
Results : CPPV8 depressed CO by 25% without shifts in its relative distribution with the exception of a noteworthy increase in adrenal perfusion. Propranolol increased arterial blood pressure, and due to a fall in heart rate, CO dropped by 25%. The kidneys and, to a lesser extent, the splanchic region and central nervous system received increased fractions of the remaining CO at the expense of skeletal muscle flow. Similar patterns were seen during SB and CPPV8 such that the combination of propranolol and CPPV8 depressed CO by 50%. The circulatory effects of verapamil were less evident but myocardial perfusion tended to increase.
Conclusions : The combination of propranolol or verapamil with CPPV does not result in any specific hemodynamic interaction in anesthetized pigs, except that the combined effect of propranolol and CPPV may severely reduce CO.     

Bariatric Surgery in Some "Central and East-European (former Eastern bloc)"Countries - Current Status and Prediction for the Next Millennium

Background: Obesity is increasing globallly, including in the formerly "Eastern Bloc" countries. Methods: A survey was made of obesity and bariatric surgery. Results: In the 8 East and Central European countries studied, with total population 300 million, roughly 43% of the population was overweight (BMI 25-30), 23% obese (BMI > 30), with about 15 million people morbidly obese (BMI > 40). From 0-10 morbidly obese individuals/100,000/year undergo bariatric surgery. Conclusion: Most countries were found to provide inadequate treatment for obesity.The majority of the morbidly obese are not treated effectively. However, health-care awareness of obesity and bariatric surgeons are slowly increasing.     

Volatile anaesthetics reduce adhesion of blood platelets under low-flow conditions in the coronary system of isolated guinea pig hearts

Background : Inhibitory effects of volatile anaesthetics on platelet aggregation have been demonstrated in several studies. However, the influence of volatile anaesthetics on intracoronary platelet adhesion has not been elucidated so far.
Methods : Isolated hearts of guinea pigs were perfused with buffer in the absence or presence of volatile anaesthetics (0.5 and 1 MAC) at constant coronary flow rates of 5 ml/min for 25 min, then 1 ml/min for 30 min and again 5 ml/min for 10 min. Before, during and after low-flow perfusion, a bolus of human platelets was applied into the coronary system. To simulate thrombogenic conditions, 0.3 U/ml human thrombin was infused during low-flow perfusion and reperfusion. The number of platelets sequestered to the endothelium was calculated from the difference between coronary in- and output of platelets. The myocardial production of lactate and consumption of pyruvate and coronary perfusion pressure were also determined.
Results : At a flow rate of 5 ml/min only about 3% of the applied platelets did not emerge from the coronary system, in any group. In contrast, 13.1±1.2% (mean±SEM) of infused platelets became adherent in low-flow perfusion in the control group without anaesthetic. The adherence was reduced with each 1 MAC isoflurane (to 6.2±1.2%), sevoflurane (to 4.4±0.9%) or halothane (to 3.2±1.5%) (each P <0.05 vs. control). Volatile anaesthetic, 0.5 MAC, did not inhibit platelet adhesion to a statistically significant extent in any case. Perfusion pressure and metabolic parameters were not statistically different between the control and the hearts exposed to anaesthetics.
Conclusion : Volatile anaesthetics in a concentration of 1 MAC can reduce the adhesion of platelets in the coronary system under reduced flow conditions. This action does not arise from vasodilation or inhibition of ischaemic stress.     

Synergistic interaction between the effects of propofol and midazolam with fentanyl on phrenic nerve activity in rabbits

Background: It has been shown that the depressive effects of both propofol and midazolam on consciousness are synergistic with opioids, but the nature of their interactions on other physiological systems, e. g. respiration, has not been fully investigated. The present study examined the effect of propofol and midazolam alone and in combination with fentanyl on phrenic nerve activity (PNA) and whether such interactions are additive or synergistic. Methods: PNA was recorded in 27 anaesthetised and artificially ventilated rabbits. In three groups, propofol, fentanyl and midazolam were administered intravenously in incremental doses to construct dose-response curves for the depressant effects of each one on PNA. In another two groups, the effect of pretreatment with either fentanyl 1 μg · kg^?1 i. v. or midazolam 0.05 mg · kg^?1 i. v. on the effects of propofol and fentanyl respectively on PNA were studied. Results: Propofol and fentanyl caused a dose-dependent depression of PNA with complete abolition at the highest total doses of 16 mg · kg^?1 i. v. and 32 μg · kg^?1 i. v., respectively. In contrast, midazolam in incremental doses to a total of 0.8 mg · kg^?1 reduced mean PNA by 63%, but approximately 12% of PNA remained at a total dose as high as 6.4 mg · kg^?1. The mean ED₅₀s, calculated from dose-response curves, were 5.4 mg · kg^?1, 3.9 μg · kg^?1 and 0.4 mg · kg^?1 for propofol, fentanyl and midazolam, respectively. Initial doses of either fentanyl 1 μg · kg^?1 i. v. or midazolam 0.05 mg · kg^?1 i. v. acted synergistically with subsequent doses of either propofol or fentanyl to abolish PNA at total doses of 8 mg · kg^?1 and 8 μg · kg^?1, respectively. Conclusion: Fentanyl has a synergistic interaction with both propofol and midazolam on PNA and hence potentially on respiration.     

Influence of dopexamine hydrochloride on haemodynamics and regulators of circulation in patients undergoing major abdominal surgery

Background: Catecholaminergic support is often used to improve haemodynamics in patients undergoing major abdominal surgery. Dopexamine is a synthetic vasoactive catecholamine with beneficial microcirculatory properties. Methods: The influence of perioperative administration of dopexamine on cardiorespiratory data and important regulators of macro- and microcirculation were studied in 30 patients undergoing Whipple pancreaticduodenectomy. The patients received randomized and blinded either 2 μg · kg^?1 · min^?1 of dopexamine (n=15) or placebo (n=15, control group). The infusion was started after induction of anaesthesia and continued until the morning of the first postoperative day. Endothelin-1 (ET-1), vasopressin, atrial natriuretic peptide (ANP), and catecholamine plasma levels were measured from arterial blood samples. Measurements were carried out after induction of anaesthesia, 2 h after onset of surgery, at the end of surgery, 2 h after surgery, and on the morning of the first postoperative day. Results: Cardiac index (CI) increased significantly in the dopexamine group (from 2.61±0.41 to 4.57±0.78 1 · min^?1 · m^?2) and remained elevated until the morning of the first postoperative day. Oxygen delivery index (DO₂I) and oxygen consumption index (VO₂I) were also significantly increased in the dopexamine group (DO₂I: from 416±91 to 717±110 ml/m² · m²; VO₂I: from 98±25 to 157±22 ml/m² · m²), being significantly higher than in the control group. pHi remained stable only in the dopexamine patients, indicating adequate splanchnic perfusion. Vasopressive regulators of circulation increased significantly only in the untreated control patients (vasopressin: from 4.37±1.1 to 35.9±12.1 pg/ml; ET-1: from 2.88±0.91 to 6.91±1.20 pg/ml). Conclusion: Patients undergoing major abdominal surgery may profit from prophylactic perioperative administration of dopexamine hydrochloride in the form of improved haemodynamics and oxygenation as well as beneficial influence on important regulators of organ blood flow.     

Systemic analgesia adapted to the children's condition

A concept of balanced analgesia using nonsteroidal anti-inflammatory drugs (NSAIDs), paracetamol (acetaminophen), opioids, and corticosteroids can also be used in patients with pre-existing illnesses. NSAIDs are the most effective treatment for acute pain of moderate intensity in children; however, these drugs should be avoided in patients at increased risk for serious side effects, e.g. patients with renal impairment, bleeding tendency, or extreme prematurity. NSAIDs can be given with minimal risks to the younger child with mild to moderate asthma, and, in these patients, the use of steroids can be encouraged; in addition to their antiemetic and analgesic action, a beneficial effect on asthma symptoms can be expected. In the non-intubated child with cerebral trauma, exaggerated sedation caused by opioids and increased bleeding tendency caused by NSAIDs must be avoided. In neonates and small infants, the oral administration of sucrose or glucose is helpful to minimize pain reaction during short uncomfortable interventions.